text: // Simple covered index query test
  
  // Include helpers for analyzing explain output.
  load("jstests/libs/analyze_plan.js");
  
  var coll = db.getCollection("covered_simple_id");
  coll.drop();
  for (i = 0; i < 10; i++) {
      coll.insert({_id: i});
  }
  coll.insert({_id: "string"});
  coll.insert({_id: {bar: 1}});
  coll.insert({_id: null});
  
  // Test equality with int value
  var plan = coll.find({_id: 1}, {_id: 1}).hint({_id: 1}).explain("executionStats");
  assert(isIndexOnly(db, plan.queryPlanner.winningPlan),
         "simple.id.1 - indexOnly should be true on covered query");
  assert.eq(0,
            plan.executionStats.totalDocsExamined,
            "simple.id.1 - docs examined should be 0 for covered query");
  
  // Test equality with string value
  var plan = coll.find({_id: "string"}, {_id: 1}).hint({_id: 1}).explain("executionStats");
  assert(isIndexOnly(db, plan.queryPlanner.winningPlan),
         "simple.id.2 - indexOnly should be true on covered query");
  assert.eq(0,
            plan.executionStats.totalDocsExamined,
            "simple.id.2 - docs examined should be 0 for covered query");
  
  // Test equality with int value on a dotted field
  var plan = coll.find({_id: {bar: 1}}, {_id: 1}).hint({_id: 1}).explain("executionStats");
  assert(isIndexOnly(db, plan.queryPlanner.winningPlan),
         "simple.id.3 - indexOnly should be true on covered query");
  assert.eq(0,
            plan.executionStats.totalDocsExamined,
            "simple.id.3 - docs examined should be 0 for covered query");
  
  // Test no query
  var plan = coll.find({}, {_id: 1}).hint({_id: 1}).explain("executionStats");
  assert(isIndexOnly(db, plan.queryPlanner.winningPlan),
         "simple.id.4 - indexOnly should be true on covered query");
  assert.eq(0,
            plan.executionStats.totalDocsExamined,
            "simple.id.4 - docs examined should be 0 for covered query");
  
  // Test range query
  var plan = coll.find({_id: {$gt: 2, $lt: 6}}, {_id: 1}).hint({_id: 1}).explain("executionStats");
  assert(isIndexOnly(db, plan.queryPlanner.winningPlan),
         "simple.id.5 - indexOnly should be true on covered query");
  assert.eq(0,
            plan.executionStats.totalDocsExamined,
            "simple.id.5 - docs examined should be 0 for covered query");
  
  // Test in query
  var plan = coll.find({_id: {$in: [5, 8]}}, {_id: 1}).hint({_id: 1}).explain("executionStats");
  assert(isIndexOnly(db, plan.queryPlanner.winningPlan),
         "simple.id.6 - indexOnly should be true on covered query");
  assert.eq(0,
            plan.executionStats.totalDocsExamined,
            "simple.id.6 - docs examined should be 0 for covered query");
  
  print('all tests pass');
  